Re: Motor suppression

"Jim McLaughlin" <[EMAIL PROTECTED]> wrote:

>"Paul Davenport" <[EMAIL PROTECTED]> wrote in message
>news:[EMAIL PROTECTED]
>> Thanks for that, put what exactly is a 'cap' what uF value?
>>
>> Ta for further advice
>
>Mr. Davenport needs a  "cookbook recipie for this, not a  dissertation on
>electronic theory.
>
>I've  been using a  Radio Shack part, a  47 microfarad electrolytic
>capacitor rated at 35 volts.  The Rat Shack part number is / was 272-1027.
>
>These are motors I recycled from when my kids used them with RC cars. I
>think the are all "540" motors, though one may be a "380", if my failing
>memory is accurate.
>
>Three of these are on each motor, one across the brush leads / contacts, and
>one from each brush to the case.
>
>The + lead from the cap is soldered to the + side of the motor brush. The -
>lead is soldered to the - side of the motor brush leads / contacts for the
>cap across the motor brushes.   On the caps to the casing, + lead from cap
>soldered to + brush contact and _ lead soldered to case on one side.   On
>the other side, - lead from cap soldered to - lead on brush / motor contact
>and + lead from cap soldered to case.

That capacitor arrangement probably won't work on a boat if the motor is ever
reversed. The electrolytic capacitor will at least not work if the voltage is
reversed, and may actually blow up due to internal pressure. Also, that size
capacitor is not that good at preventing Radio Frequency Interference (RFI) to
a radio.

Use ceramic disc capacitors rated at 0.1 microfarads, rated at least 50 or
more volts (they are usually in the 100 volt or more range) . Alternatively,
go to a hobby store that sells RC cars, and they will usually have capacitors
to suppress RFI. Be sure to tell them you will be using them on a reversible
motor, in case they try to sell you a polarized capacitor. If the package says
to hook a particular terminal of the capacitor to the positive, don't buy it.

As everyone else has said, hook up three of these to the motor. Two, from each
terminal to the case of the motor, and a third from one terminal to the other
on the motor.

>Jim McLaughlin

Jerry